Make FunctionControl flag available

Change-Id: Ib706c1fffca127262fa2a4d26e69659396eb90df

Author: piotrkira

IGC/common/igc_flags.def

@@ -331,7 +331,7 @@ DECLARE_IGC_REGKEY(bool, DisableDualBlendSource,        false, "Force the compil
 DECLARE_IGC_REGKEY(bool, ForceDisableSrc0Alpha,         false, "Force the compiler to skip sending src0 alpha. Only works if we are sure alpha to coverage and alpha test is off", false)
 DECLARE_IGC_REGKEY(bool, EnableLTO,                     true,  "Enable link time optimization", false)
 DECLARE_IGC_REGKEY(bool, EnableLTODebug,                false, "Enable debug information for LTO", true)
-DECLARE_IGC_REGKEY(DWORD, FunctionControl,              0,     "Control function inlining/subroutine/stackcall. See value defs in igc_flags.hpp.", false)
+DECLARE_IGC_REGKEY(DWORD, FunctionControl,              0,     "Control function inlining/subroutine/stackcall. See value defs in igc_flags.hpp.", true)
 DECLARE_IGC_REGKEY(bool, EnableStackCallFuncCall,       false, "If enabled, the default function call mode will be set to stack call. Otherwise, subroutine call is used.", false)
 DECLARE_IGC_REGKEY(DWORD, OCLInlineThreshold,           512,  "Setting OCL inline thershold", false)
 DECLARE_IGC_REGKEY(bool, DisableAddingAlwaysAttribute,  false, "Disable adding always attribute", true)

documentation/configuration_flags.md

@@ -50,6 +50,7 @@ $ export IGC_ShaderDumpEnable=1
 - **EnableVISADumpCommonISA** - Enable VISA Dump Common ISA
 - **EnableVISAOutput** - Enable VISA GenISA output
 - **EnableVISASlowpath** - Enable VISA Slowpath. Needed to dump .visaasm
+- **FunctionControl** - Control function inlining/subroutine/stackcall. See value defs in igc_flags.hpp
 - **ForceRPE** - Force RPE (RegisterEstimator) computation if > 0. If 2, force RPE per inst
 - **ForceOCLSIMDWidth** - Force using specified SIMD width. Possible values: 0 (off), 8, 16, 32.
 - **InterleaveSourceShader** - Interleave the source shader in asm dump